Tilted light sheet microscopy with 3D point spread functions (TILT3D) combines a novel, tilted light sheet illumination strategy with long axial range point spread functions (PSFs) for ...low-background, 3D super-localization of single molecules as well as 3D super-resolution imaging in thick cells. Because the axial positions of the single emitters are encoded in the shape of each single-molecule image rather than in the position or thickness of the light sheet, the light sheet need not be extremely thin. TILT3D is built upon a standard inverted microscope and has minimal custom parts. The result is simple and flexible 3D super-resolution imaging with tens of nm localization precision throughout thick mammalian cells. We validate TILT3D for 3D super-resolution imaging in mammalian cells by imaging mitochondria and the full nuclear lamina using the double-helix PSF for single-molecule detection and the recently developed tetrapod PSFs for fiducial bead tracking and live axial drift correction.
This article describes and problematizes the skills that are used when researching analogue archives. The article deals with the process that operates when a researcher finds small details in ...archival records that makes it possible to generate a story. Whether it is skill or luck that enables one to find the phenomena that create meaning is also discussed. The empirical example is fetched from the “Swedish Town project” that was initiated with the aim to write a new kind of urban history in the 1940s by Swedish art historian Gregor Paulsson. The researcher Börje Hanssen conducted field work in the city of Helsingborg in southern Sweden during the summers in 1942, 1943 and 1944. The “Swedish Town”-project explored urban history through both traditional sources such as archives, but also by interviews with contemporary town inhabitants and photographs. In the article we meet both Hanssen and some of his interviewees, and his working methods, his texts and some photographs are being analyzed. Börje Hanssen later became an influential ethnologist and in this article we encounter him in the beginning of his career. In order to examine the role played by one small detail in a large amount of material, and how such a detail can influence the researcher’s inter- pretations, Roland Barthes concepts of punctum and studium are used in the article, in order to create meaning out of small, everyday and often seemingly insignificant phenomena. Punctum and studium are fruitful analytical tools, not only in analyzing photographs, which was Barthes original use of the concept but also in other contexts, in this case archival records. The article thus discusses when a detail becomes the punctum that changes the researcher’s mindset and enables new knowledge to be produced.
Yeast glycolytic oscillations have been studied since the 1950s in cell‐free extracts and intact cells. For intact cells, sustained oscillations have so far only been observed at the population ...level, i.e. for synchronized cultures at high biomass concentrations. Using optical tweezers to position yeast cells in a microfluidic chamber, we were able to observe sustained oscillations in individual isolated cells. Using a detailed kinetic model for the cellular reactions, we simulated the heterogeneity in the response of the individual cells, assuming small differences in a single internal parameter. This is the first time that sustained limit‐cycle oscillations have been demonstrated in isolated yeast cells.
Database
The mathematical model described here has been submitted to the JWS Online Cellular Systems Modelling Database and can be accessed at http://jjj.biochem.sun.ac.za/database/gustavsson/index.html free of charge.
Previously, sustained oscillations have only been observed at the population level. Using optical tweezers to position yeast cells in a microfluidic chamber, where the cell environment was spatially and temporally controlled, sustained oscillations in individual, isolated cells were observed. The heterogeneous response of the cells was simulated using a detailed kinetic model, assuming small differences in a single internal parameter
Oscillations are widely distributed in nature and synchronization of oscillators has been described at the cellular level (e.g. heart cells) and at the population level (e.g. fireflies). Yeast ...glycolysis is the best known oscillatory system, although it has been studied almost exclusively at the population level (i.e. limited to observations of average behaviour in synchronized cultures). We studied individual yeast cells that were positioned with optical tweezers in a microfluidic chamber to determine the precise conditions for autonomous glycolytic oscillations. Hopf bifurcation points were determined experimentally in individual cells as a function of glucose and cyanide concentrations. The experiments were analyzed in a detailed mathematical model and could be interpreted in terms of an oscillatory manifold in a three‐dimensional state‐space; crossing the boundaries of the manifold coincides with the onset of oscillations and positioning along the longitudinal axis of the volume sets the period. The oscillatory manifold could be approximated by allosteric control values of phosphofructokinase for ATP and AMP.
Database
The mathematical models described here have been submitted to the JWS Online Cellular Systems Modelling Database and can be accessed at http://jjj.mib.ac.uk/webMathematica/UItester.jsp?modelName=gustavsson5.
Database section added 14 May 2014 after original online publication
Conditions for autonomous glycolytic oscillations and Hopf bifurcations, as a function of glucose and cyanide concentrations, were determined studying individual yeast cells in a microfluidic chamber. A detailed model lead to the interpretation of results in terms of an oscillatory manifold in a three‐dimensional state‐space. This manifold could be approximated by allosteric control values of phosphofructokinase for ATP and AMP.
Cell signaling, gene expression, and metabolism are affected by cell-cell heterogeneity and random changes in the environment. The effects of such fluctuations on cell signaling and gene expression ...have recently been studied intensively using single-cell experiments. In metabolism heterogeneity may be particularly important because it may affect synchronisation of metabolic oscillations, an important example of cell-cell communication. This synchronisation is notoriously difficult to describe theoretically as the example of glycolytic oscillations shows: neither is the mechanism of glycolytic synchronisation understood nor the role of cell-cell heterogeneity. To pin down the mechanism and to assess its robustness and universality we have experimentally investigated the entrainment of glycolytic oscillations in individual yeast cells by periodic external perturbations. We find that oscillatory cells synchronise through phase shifts and that the mechanism is insensitive to cell heterogeneity (robustness) and similar for different types of external perturbations (universality).
Preserving the past to serve the future Palmsköld, Anneli; Gustavsson, Karin; Rosenqvist, Johanna
Formakademisk,
2023, Letnik:
16, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Lilli Zickerman (1858–1949) was an entrepreneur who took part in organising the Swedish handicraft associations in the late 19th century. She was also a pioneer in the archives and active in the ...feminine sphere of textile handicraft. From 1914– 1931 she conducted a huge inventory called Swedish Folk Textile Art that consists of more than 24,000 photographs and descriptions of vernacular textiles and manuscripts for a planned series of books and films. By mapping textile handicrafts, she aimed to preserve traditional textile craft techniques to inspire their continued production. Her intention was to create an archive for the inspiration and education of future textile artists. The inventory has had effects that are still apparent today; this paper illuminates the ways in which Zickerman's ideas about textile handicrafts have contributed to the continuation of Swedish cultural heritage and how it has become an authorised heritage discourse that continues to guide the scholars and practitioners involved in the history of textiles and their production. Here, we will present the first article within an ongoing project on Swedish Folk Textile Art and how it was conducted. We will contextualise the ideas and knowledge that it contains by focusing on Zickerman's intention to preserve the past to serve the future. From a critical craft perspective, we will discuss geographical mapping as a method for investigating the inventtory; the inclusion and exclusion of geographical areas, textile techniques, materials and people; the ideas and the knowledge that are expressed in the inventory; and the networks that it created. By doing so, we aim to highlight the connections between people, between people and materials, and between history and the current day.
The function of the neuronal synapse depends on the dynamics and interactions of individual molecules at the nanoscale. With the development of single-molecule super-resolution microscopy over the ...last decades, researchers now have a powerful and versatile imaging tool for mapping the molecular mechanisms behind the biological function. However, imaging of thicker samples, such as mammalian cells and tissue, in all three dimensions is still challenging due to increased fluorescence background and imaging volumes. The combination of single-molecule imaging with light sheet illumination is an emerging approach that allows for imaging of biological samples with reduced fluorescence background, photobleaching, and photodamage. In this review, we first present a brief overview of light sheet illumination and previous super-resolution techniques used for imaging of neurons and synapses. We then provide an in-depth technical review of the fundamental concepts and the current state of the art in the fields of three-dimensional single-molecule tracking and super-resolution imaging with light sheet illumination. We review how light sheet illumination can improve single-molecule tracking and super-resolution imaging in individual neurons and synapses, and we discuss emerging perspectives and new innovations that have the potential to enable and improve single-molecule imaging in brain tissue.
The development of imaging techniques beyond the diffraction limit has paved the way for detailed studies of nanostructures and molecular mechanisms in biological systems. Imaging thicker samples, ...such as mammalian cells and tissue, in all three dimensions, is challenging due to increased background and volumes to image. Light sheet illumination is a method that allows for selective irradiation of the image plane, and its inherent optical sectioning capability allows for imaging of biological samples with reduced background, photobleaching, and photodamage. In this review, we discuss the advantage of combining single-molecule imaging with light sheet illumination. We begin by describing the principles of single-molecule localization microscopy and of light sheet illumination. Finally, we present examples of designs that successfully have married single-molecule super-resolution imaging with light sheet illumination for improved precision in mammalian cells.
The Swedish folklore collector Eva Wigström collaborated in the 1890s with the young artist and illustrator Gisela Trapp. They both lived in Helsingborg in the south of Sweden and shared many ...interests, despite a difference in age of about 40 years. In this article we are introduced to Wigström’s work as an author and folklore collector, and the cooperation between the two women is described. Wigström also inspired Gisela Trapp to collect folklore, and the difference in their backgrounds is discussed, as are the differences in how their personal papers have been archived and how this has affected what we know today about their work. The role of non-scholars in research is also discussed.
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